The time taken by a boat to go 48 km downstream is 40% of the tim

SOLUTION

Let the speed of boat in still water be x km/h

And the speed of stream be y km/h

So, the downstream speed of boat = (x + y) km/h

And the upstream speed of boat = (x – y) km/h

According to the question:

\(\frac{{48}}{{x\; + \;y}}\; = \;\left[ {\frac{{60}}{{x\;-\;y}}} \right]\; \times \frac{{40}}{{100}}\)

\(\Rightarrow {\rm{\;}}\frac{4}{{x\; + \;y}}\; = \;\left[ {\frac{5}{{x\;-\;y}}} \right]\; \times \frac{2}{5}\)

\(\Rightarrow {\rm{\;}}\frac{2}{{x\; + \;y}} = \frac{1}{{x\;-\;y}}\)

⇒ 2x – 2y = x + y

⇒ x = 3y

\(\Rightarrow {\rm{\;}}\frac{x}{y} = \frac{3}{1}\)